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All
dermatologists will see ample psoriasis over the course of their careers,
and the majority of these patients are treated primarily with
topical therapies. Certainly extensive and/or life-altering psoriasis
deserves systemic treatment or phototherapy, and the presence of concomitant
joint disease typically requires systemic treatment. However, topical
medications, particularly corticosteroids, can be successfully utilized
in all psoriasis patients, as they are highly effective, very safe, provide
relief from symptomatic lesions, and, for those on systemic therapy, help
minimize the exposure to systemic agents.
There are many factors that may affect the
efficacy of topical preparations. Commonly discussed are the ability of
an active agent to: 1) partition from the vehicle, 2) penetrate through
the stratum corneum, and 3) bind its cytoplasmic receptor and exert effect
on transcription, etc. One overlooked aspect of successful treatment is
adherence; if a medication does not get taken out of the cabinet, the components
of efficacy mentioned above are irrelevant. We know that dermatology patients
frequently don’t use medications as instructed (and frequently lie about
it!).1-2
Two of the most common approaches to the
topical treatment of psoriasis are clobetasol propionate, and the use of
a class I or II corticosteroid with calcipotriene or calcipotriol. Often,
however, there seems to be a discrepancy between the robust efficacy seen
in clinical trials and the limited effectiveness seen in clinical practice,
a discord likely explained by patient behaviors.
Clobetasol is commercially available in at
least 7 different vehicles; selection of the appropriate preparation is
critical to getting close to the efficacy reported in clinical trials.
The notion that ointments are a "more potent" delivery system is dogma
that is refuted by the efficacy seen with some of the newer, non-occlusive
preparations discussed herein and elsewhere.3 Far
more important than the moisturizing properties of the vehicle is the patient’s
propensity to use the medication.
The ideal topical medication is technically
easy to apply, not messy, and has a simple dosing regimen. Novel preparations
of clobetasol in lotion (Clobex®), spray (Clobex®) and foam (Olux®)
vehicles have evolved to address patient preferences in topical therapy.
The stout efficacy of these preparations may in part be explained by enhanced
adherence: psoriasis patients are known to prefer less messy preparations.4 A
combination betamethasone dipropionate/calcipotriene ointment (Taclonex® in
the US), has impressive efficacy with only once-daily application. As discussed
herein, its efficacy is remarkable and may be due to intrinsic properties
of the medication as well as the facile dosing regimen. And although not
definitively proven, once-daily dosing is likely to lead to better adherence
and subsequent efficacy.
Topical therapy is not without limitations.
Traditionally, tachyphalyxis has been defined as decreasing response to
a medication with increasing use. Perhaps a better definition is decreased
response to a medication with decreased use. Patients that use
their medication tend to get better, while those that do not tend not to
improve.5 The
original study reviewed herein by Carroll et al from 2004 looked at several
measures of adherence to a prescribed regimen for psoriasis, and provides
meaningful implications for clinical practice. Among the findings as to
why efficacy in clinical trials does not always seem to extrapolate to
clinical practice, one reason may be that in the "controlled" trial world
there are motivated patients given explicit instructions, multiple follow
up visits, and cash as part of the study. Therefore, these study subjects
tend to use their medications better than do clinic patients.
In summary, when chosen properly, topical
therapy for psoriasis is safe and cost-effective. Patients with chronic
skin diseases generally want to get better and want to use their medication.
We frequently ask much of them, by providing inadequate patient education,
recommending complex regimens without taking patient preference into account,
and not arranging follow-up that reinforces positive adherence. It is unreasonable
to expect that a patient with psoriasis will not improve with 1 or 2 weeks
of clobetasol therapy regardless of previous treatment failures. Perhaps
by taking the time to understand the patient’s vehicle preferences, and
by scheduling short (1-2 weeks) follow-up visits, we can improve the outcomes
of our psoriasis patients and strengthen the physician/patient relationship.
References
| 1. |
Krejci-Manwaring
J, Tusa MG, Carroll C, et al. Stealth
monitoring of adherence to topical medication: adherence is very poor
in children with atopic dermatitis. J Am Acad Dermatol. 2007
Feb;56(2):211-216. Epub 2006 Nov 13. |
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| 2. |
Carroll
CL, Feldman SR, Camacho FT, Manuel JC, Balkrishnan R. Adherence
to topical therapy decreases during the course of an 8-week psoriasis
clinical trial: commonly used methods of measuring adherence to topical
therapy overestimate actual use. J Am Acad Dermatol. 2004
Aug;51(2):212-216. |
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| 3. |
Warino
L, Balkrishnan R, Feldman SR. Clobetasol
propionate for psoriasis: are ointments really more potent? J
Drugs Dermatol. 2006 Jun;5(6):527-532. Review. |
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| 4. |
Housman
TS, Mellen BG, Rapp SR, Fleischer AB Jr, Feldman SR. Patients
with psoriasis prefer solution and foam vehicles: a quantitative assessment
of vehicle preference. Cutis. 2002 Dec;70(6):327-332. |
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| 5. |
Carroll
CL, Feldman SR, Camacho FT, Balkrishnan R. Better
medication adherence results in greater improvement in severity of
psoriasis. Br J Dermatol. 2004 Oct;151(4):895-897. |
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